Tran was later arrested on suspicion of drunken driving. It wasn't immediately clear if he had an attorney.

The San Francisco Chronicle reports that the two firefighters in the firetruck were not injured. The newspaper says Tran and a female passenger in the Tesla were taken to San Jose Regional Medical Center with minor injuries.

Tesla's semi-autonomous Autopilot mode has come under scrutiny following other recent crashes. The carmaker says the function is not designed to avoid a collision and warns drivers not to rely on it entirely.

It was unclear whether Autopilot was activated. Tesla says in a statement that it "has not yet received any data from the car, but we are working to establish the facts of the incident."